1. Field of the Invention
The invention relates generally to applications in the construction industry known as xe2x80x9ctie backsxe2x80x9d, or xe2x80x9csoil nailingxe2x80x9d.
2. Description of Related Art
Formations of natural substrate, such as hills of rocks or soil, have been known to undergo slides and sloughing over as a result of a disturbance. This disturbance may be natural, such as an earthquake, surface and subsurface water action, or manmade, such as vehicular traffic. For example, excessive rainfall may cause mudslides in which dirt and other natural substrate of a hill slough over onto adjacent land. This phenomena occurs not only with natural occurring formations, but with artificial, manmade formations as well, such as excavations created for building foundations or easements for roadways. Unless the vertical faces of these formations are stabilized, retained or held back, the formations may very well collapse leading to catastrophic results.
Tie backs or soil nails are used to restrain, stabilize, retain, or hold back a substantially vertical face of a formation of natural substrate in order to prevent the natural substrate from sloughing over. Therefore, it is crucial that a soil nail, or tie back, structure be capable of restraining a natural formation without any compromise in strength and endurance.
In accordance with the present invention, a structure and associated method are disclosed. The invention comprises both a structure and an associated method for stabilizing a formation having a substantially vertical face.
In one aspect, the invention comprises a soil nail apparatus, or system. The soil nail apparatus comprises a tendon, a plate, a tube, an adhesive material, and an anchor. The plate has a bore through which the tendon extends. The bore has a bore diameter. The tube is disposed adjacent to the bore of the plate such that a portion of the tendon extends through the bore of the plate and into the tube. The tube has an outer diameter greater than the bore diameter. The adhesive material is disposed within the tube. The anchor is coupled to the plate.
The tendon may comprise a metallic or non-metallic material. The plate, tube, and anchor may each comprise a non-metallic material. The non-metallic material of the soil nail apparatus comprises a fiber reinforced polymer, or FRP, material. The fiber reinforced polymer material comprises a suitable reinforced fiber and a suitable resin formed into a structural matrix wherein the type of reinforced fiber and the type of resin is a function of the intended environment of use. The tendon may comprise a single strand or multiple strands of a fiber reinforced polymer material. The tendon comprises a non-threaded surface. The tendon may include a smooth or deformed surface.
The bearing plate and the tube may also comprise a non-metallic material, such as a fiber reinforced polymer material. The tube includes a plurality of injection ports defined in a side wall. An inner surface of the tube may be deformed to increase adhesion to the adhesive material. The tube, may include an end cap with an exit aperture.
The adhesive material comprises a chemical anchoring material, such as epoxy. The adhesive material also comprises cementitious grout. The anchor comprises a headed stud coupled to a far surface of the plate.
The soil nail apparatus further comprises a final concrete facing encapsulating the tube, the plate, and the anchor.
In another aspect, the invention comprises a heading device that is adapted for securing a soil nail. The heading device comprises a non-metallic plate, a non metallic tube, an adhesive material, and a non-metallic anchor.
The non-metallic plate has a near surface, a far surface, and a bore with a bore diameter. The hollow non-metallic tube has an outer diameter greater than the bore diameter. The tube is disposed adjacent to the far surface and the bore of the plate. The adhesive material is disposed within the tube. The non-metallic anchor is coupled to the far surface of the plate. The non-metallic anchor comprises a headed stud. The headed stud may also be attached to a second: plate separate from the plate through which the tendon extends. The non-metallic plate, the non-metallic tube, and the non-metallic anchor may each comprise a fiber reinforced polymer material.
The invention further comprises methods for stabilizing a formation having a substantially vertical face. In one aspect, a method comprises: forming a hole into the formation via the substantially vertical face; inserting a tendon into the hole with an exposed portion of the tendon protruding out from the hole; filling the hole with grout; placing a plate over the exposed portion of the tendon; disposing a tube over the exposed portion of the tendon; and filling the tube with an adhesive material.
The method further comprises the following, each of which may be practiced in combination with or separately from the others: deforming a surface of the tendon; deforming an inner surface of the tube; forming the tendon out of a fiber reinforced polymer material; forming the tendon comprises grouping multiple strands of a fiber reinforced polymer material; and placing a final concrete facing over the plate, tube, and stud.
Forming the hole in the formation comprises drilling into the vertical face of the formation. Filling the tube with an adhesive material comprises injecting the adhesive material into the tube via injection ports on a side wall of the tube, or placing adhesive material into the tube prior to disposing the tube over the exposed portion of the tendon.
In another aspect, the invention comprises an additional method for stabilizing a formation having a substantially vertical facing. The method comprises: inserting a soil nail into a hole in the formation via the vertical facing; exerting load into the hill formation with the soil nail; transferring load from the soil nail to an adhesive material disposed on a portion of the soil nail protruding from the hole in the formation; transferring load from the adhesive to a tube disposed over the protruding portion of the soil nail; and transferring load from the tube to a plate disposed adjacent to the soil nail.
The method further comprises the following: transferring load from the plate to an anchor coupled to the plate; transferring load from the anchor to a final concrete facing embedding the anchor; and transferring load from the final concrete facing toward the vertical facing of the hill formation.
The invention, now having been briefly summarized,,may be better visualized by turning to the following drawings wherein like elements are referenced by like numerals.